How can I achieve a crumpling effect?
Here's how you might do it using shape keys.

First model the fork as you would normally, but include plenty of edge loops around the handle and prongs (tines?). Save this as your base shape, create a new shape key, then enter Edit mode and deform the object manually by selecting and dragging nodes. Make sure the undeformed parts of the object are moved down by a suitable distance so that the deformation looks believable.

You can then animate between the base shape and the deformed shape key by animating the shape key's value parameter: